Vehicle control system

Abstract

To appropriately stop a vehicle at a target stop position.SOLUTION: A vehicle control device comprises: a residual distance obtaining part that obtains change with time of residual distances up to a target stop position; a control part that controls a braking device so that first braking force is applied to a vehicle in order to stop the vehicle at the target stop position; and a slip-down detecting part that detects slip-down of the vehicle, on the basis of the change with time of the residual distances. When the slip-down of the vehicle is detected, the control part controls a braking device so that second braking force larger than the first braking force is applied to the vehicle.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a vehicle control device.

Background Art

[0002] Braking control for stopping a vehicle at a target stop position is known. For example, in Patent Document 1 below, when the remaining distance from the current position of the vehicle to the target stop position is a first distance, the feedback gain of the acceleration feedback system is increased more than when the remaining distance is a second distance greater than the first distance, so that the vehicle can be surely stopped at the target stop position. Further, in Patent Document 2 below, the remaining distance from the current position of the vehicle to the stop position is acquired, and when the remaining distance becomes less than or equal to a preset deceleration start distance, the speed of the vehicle is decelerated, so that the vehicle can be stopped at the stop position without impairing the riding comfort.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In this type of braking assistance control, in order to reduce the impact on the occupant at the time of stopping, control may be performed to loosen the braking amount immediately before the vehicle stops. However, when the target stop position is set on a slope, the vehicle may slide down due to the gradient when the brake is loosened. In this case, the vehicle cannot be stopped at the target stop position.

[0005] Therefore, an object of the present disclosure is to provide a vehicle control device capable of appropriately stopping a vehicle at a target stop position.

Means for Solving the Problems

[0006] In one embodiment, a vehicle control device is provided that is mounted on a vehicle equipped with a braking system and performs braking control to stop the vehicle at a target stopping position. The device comprises a remaining distance acquisition unit that acquires the time change of the remaining distance to the target stopping position, a control unit that controls the braking system to apply a first braking force to the vehicle in order to stop the vehicle at the target stopping position, and a sliding detection unit that detects the vehicle sliding down based on the time change of the remaining distance. When the sliding down of the vehicle is detected by the control unit, it controls the braking system to apply a second braking force to the vehicle that is greater than the first braking force.

[0007] In the vehicle control device according to this embodiment, when a vehicle is detected to be sliding backward, a second braking force greater than the first braking force is applied to the vehicle. Therefore, even if the target stopping position is set on a slope, the vehicle's backward movement is suppressed. Consequently, the vehicle can be stopped appropriately at the target stopping position.

[0008] In one embodiment, the slip detection unit may determine that the vehicle has slipped when the remaining distance continuously increases for a predetermined period of time or longer. In this case, the vehicle's slippage can be detected more reliably.

[0009] In one embodiment, the system may further include a gradient acquisition unit that acquires the gradient angle of the road surface on which the vehicle is traveling, and the second braking force may be increased as the gradient angle increases. By increasing the second braking force as the gradient angle increases, the vehicle can be reliably stopped from sliding backward. [Effects of the Invention]

[0010] According to one aspect and various embodiments of the present invention, a vehicle can be appropriately stopped at a target stopping position. [Brief explanation of the drawing]

[0011] [Figure 1] This is a block diagram showing the functional configuration of a vehicle control device according to one embodiment. [Figure 2]This is a diagram illustrating the target stopping position. [Figure 3] (a) is a graph showing an example of the change in vehicle speed over time, and (b) is a graph showing an example of the change in remaining distance to the target stopping position over time. [Figure 4] This is a flowchart showing the processing flow of the vehicle control system. [Modes for carrying out the invention]

[0012] Hereinafter, various embodiments of vehicle control devices will be described in detail with reference to the drawings. Note that the same or corresponding parts will be denoted by the same reference numerals in each drawing, and redundant descriptions of the same or corresponding parts will be omitted.

[0013] Figure 1 is a block diagram showing the functional configuration of a vehicle control device according to one embodiment. The vehicle control device 10 shown in Figure 1 is mounted on a vehicle 1 and performs braking control to stop the vehicle 1 at a target stopping position. Braking control is a control that decelerates the vehicle 1 without any driving operation by the driver of the vehicle 1.

[0014] The vehicle 1 equipped with the vehicle control device 10 is, for example, a large vehicle such as a truck, trailer, or bus. However, the vehicle 1 may also be a small vehicle. As shown in Figure 1, the vehicle 1 is equipped with a GPS (Global Positioning System) receiver 2, an external sensor 3, an internal sensor 4, a map database 5, a braking device 6, and the vehicle control device 10.

[0015] The GPS receiver 2 receives signals from three or more GPS satellites to acquire the position information of the vehicle 1. This position information includes, for example, information regarding the latitude and longitude of the vehicle 1. The GPS receiver 2 outputs the measured position information of the vehicle 1 to the vehicle control device 10. The vehicle 1 may also be equipped with other devices that acquire the position information of the vehicle 1, such as an inertial navigation system, instead of the GPS receiver 2.

[0016] The external sensor 3 acquires the surrounding information of the vehicle 1. The surrounding information includes information regarding the position, shape, color, etc. of the objects existing around the vehicle 1. Examples of the objects existing around the vehicle 1 include other vehicles, obstacles, pedestrians, traffic signals, road signs, and road markings, etc. The external sensor 3 may be, for example, a camera.

[0017] The camera images the front of the vehicle 1. As an example, the camera is provided on the windshield of the vehicle 1. The camera may be a monocular camera or a stereo camera. The stereo camera has two imaging units arranged to reproduce binocular parallax. The imaging information of the stereo camera also includes information in the depth direction.

[0018] The external sensor 3 is not limited to a camera and may be a radar sensor or the like. The radar sensor transmits radio waves or light to the periphery of the vehicle 1 and detects an object by receiving the radio waves or light reflected by the object. As the radar sensor, for example, a millimeter-wave radar or a lidar (Laser Imaging Detection and Ranging) is used.

[0019] The internal sensor 4 collects driving information regarding the vehicle 1. The driving information includes, for example, at least one of the vehicle speed, acceleration, and yaw rate. That is, the internal sensor 4 includes at least one of a vehicle speed sensor, an acceleration sensor, and a yaw rate sensor.

[0020] The vehicle speed sensor detects the speed of the vehicle 1. As the vehicle speed sensor, for example, a wheel speed sensor provided on the wheel of the vehicle 1 or a drive shaft that rotates integrally with the wheel to detect the rotational speed of the wheel is used. The acceleration sensor detects the acceleration of the vehicle 1. The acceleration sensor may include a longitudinal acceleration sensor that detects the longitudinal acceleration of the vehicle 1 and a lateral acceleration sensor that detects the lateral acceleration of the vehicle 1. The yaw rate sensor detects the yaw rate (rotational angular velocity) around the vertical axis of the center of gravity of the vehicle 1. As the yaw rate sensor, for example, a gyro sensor is used.

[0021] The map database 5 is a storage device that stores map information. The map database 5 is constituted by, for example, an HDD (Hard Disk Drive) mounted on the vehicle 1. The map information includes, for example, the position information of roads, information regarding road shapes, traffic signals, stop lines, intersections, parking spaces, and the like. The information regarding road shapes includes, for example, information regarding the width of lanes, the gradient angle of the road surface, the type of road shape (curve section or straight section), and the curvature of lanes. Note that the map database 5 may not be mounted on the vehicle 1 and may be arranged in a facility such as an information processing center that can communicate with the vehicle 1.

[0022] The braking device 6 operates the brakes of the vehicle 1 based on a control signal from the vehicle control device 10. The braking device 6 is, for example, a brake actuator that controls a brake system and applies a braking force to the wheels of the vehicle 1. As the brake system, for example, a hydraulic brake system is used.

[0023] The vehicle control device 10 is an electronic control unit having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a CAN (Controller Area Network) communication circuit, and the like. The vehicle control device 10 is connected to a network that communicates using, for example, the CAN communication circuit, and is communicably connected to each component of the vehicle 1. The vehicle control device 10 realizes various functions described later by, for example, operating the CAN communication circuit based on a signal output by the CPU to input and output data, storing the data in the RAM, loading a program stored in the ROM into the RAM, and executing the program loaded into the RAM. The vehicle control device 10 may be constituted by a plurality of electronic control units.

[0024] The vehicle control device 10 is communicatively connected to the GPS receiver 2, external sensor 3, internal sensor 4, map database 5, and braking device 6. The vehicle control device 10 receives various information from the GPS receiver 2, external sensor 3, internal sensor 4, and map database 5, and controls the braking device 6 so that the vehicle 1 stops at the target stopping position. As shown in Figure 1, the vehicle control device 10 has a functional configuration that includes a vehicle information acquisition unit 11, a surrounding information acquisition unit 12, a target stopping position setting unit 13, a remaining distance acquisition unit 14, a target deceleration determination unit 15, a control unit 16, and a sliding detection unit 17.

[0025] The vehicle information acquisition unit 11 acquires vehicle information, including the location information and vehicle speed information of vehicle 1. For example, the vehicle information acquisition unit 11 acquires the location information of vehicle 1 measured by the GPS receiver unit 2 and the speed information of vehicle 1 measured by the internal sensor 4. The surrounding information acquisition unit 12 acquires surrounding information of vehicle 1 measured by the external sensor 3. For example, based on various information acquired from the external sensor 3 and the map database 5, the surrounding information acquisition unit 12 acquires the location information of obstacles, pedestrians, traffic lights, road signs and road markings, and the gradient angle of the road surface in the direction of travel of vehicle 1 as surrounding information. The surrounding information acquisition unit 12 functions as a gradient acquisition unit that acquires the gradient angle of the road surface.

[0026] The target stopping position setting unit 13 sets a target stopping position where the vehicle 1 should stop. The target stopping position is, for example, a stop line on the route the vehicle 1 is traveling on. The target stopping position may also be a parking space where the vehicle 1 is parked. The target stopping position setting unit 13 acquires information about the stopping position (for example, location information of a stop line or parking space) contained in the map information stored in the map database 5, for example, and sets a position around the acquired stopping position as the target stopping position. Figure 2 is a diagram illustrating the target stopping position. In the example shown in Figure 2, there is a stop line L in the middle of the slope on which the vehicle 1 is traveling. This slope is an uphill slope with a gradient angle θ. The target stopping position setting unit 13 sets the position before the stop line L that is in front of the vehicle 1 as the target stopping position TP.

[0027] The target stopping position setting unit 13 may also set the target stopping position TP based on surrounding information acquired by the external sensor 3. For example, the target stopping position setting unit 13 detects the target stopping position TP by performing pattern matching using image patterns for each type of object that have been stored in advance, based on the image of the area in front of the vehicle 1 captured by the camera. For example, if there is a stop line L in front of the vehicle 1, the target stopping position setting unit 13 may extract the sign and the white line extending in the width direction of the road from the captured image, recognize the stop line L using image recognition technology, and set the position before the stop line L as the target stopping position TP.

[0028] The remaining distance acquisition unit 14 acquires the time change of the remaining distance D from the vehicle 1 to the target stopping position TP. For example, the remaining distance D is calculated based on the position information of the stop line L included in the map information and the position information of the vehicle 1. Alternatively, the remaining distance acquisition unit 14 may acquire the remaining distance D based on the depth direction information included in the image captured by the stereo camera, without using map information. The remaining distance acquisition unit 14 periodically or continuously detects the remaining distance D and acquires the time change of the remaining distance D.

[0029] The target deceleration determination unit 15 determines the target deceleration required to stop the vehicle 1 at the target stopping position TP. The target deceleration is the deceleration required to start decelerating the vehicle 1 at the deceleration start position P1 and stop the vehicle 1 at the target stopping position TP. The deceleration start position P1 is a position one deceleration start distance d1 before the target stopping position TP. For example, the target deceleration determination unit 15 sets the target deceleration based on the speed of the vehicle 1 and the remaining distance D to the target stopping position TP. Deceleration represents negative acceleration. In other words, a large deceleration means a small acceleration.

[0030] The control unit 16 controls the operation of the braking device 6. For example, when the remaining distance D to the target stopping position TP becomes smaller than the deceleration start distance d1, the control unit 16 activates the braking device 6 and starts deceleration. At this time, the control unit 16 applies a braking force (hereinafter referred to as "first braking force") to the vehicle 1 so that the vehicle's deceleration reaches the target deceleration. That is, when the vehicle 1 reaches the deceleration start position P1, the first braking force is applied to the vehicle 1 and the deceleration of the vehicle 1 begins.

[0031] Furthermore, the control unit 16 reduces the first braking force applied to the vehicle 1 when the vehicle 1 reaches the deceleration reduction position P2. The deceleration reduction position P2 is a position between the deceleration start position P1 and the target stop position TP, and is a position one deceleration reduction distance d2 before the target stop position TP. Figure 3(a) is a graph showing an example of the time change of the vehicle 1's speed due to braking control, and Figure 3(b) is a graph showing an example of the time change of the remaining distance D to the target stop position TP due to braking control. In Figure 3, time T0 is the time when the vehicle 1 reaches the deceleration start position P1, and time T1 is the time when the vehicle 1 reaches the deceleration reduction position P2.

[0032] As shown in Figures 3(a) and 3(b), when vehicle 1 reaches the deceleration start position P1 (time T0), the control unit 16 applies a first braking force to vehicle 1. As a result, vehicle 1 approaches the target stopping position TP while decelerating. Subsequently, when vehicle 1 reaches the deceleration easing position P2 (time T1), the first braking force acting on vehicle 1 is eased. This makes the deceleration of vehicle 1 gradual, and the rate of decrease of the remaining distance D per unit time decreases. By making the deceleration of vehicle 1 gradual in this way, the vehicle can be stopped smoothly, thus improving the ride comfort for the occupants. The control unit 16 may also gradually ease the braking force applied to vehicle 1 as vehicle 1 approaches the target stopping position TP.

[0033] As shown in Figure 2, if the target stopping position TP is set on a slope, releasing the braking force of vehicle 1 may cause vehicle 1 to slide backward. Here, sliding backward means that vehicle 1 moves backward away from the target stopping position TP due to the slope of the road surface. The sliding detection unit 17 detects the sliding of vehicle 1 based on the time change of the remaining distance D to the target stopping position TP.

[0034] In the example shown in Figure 3(b), the remaining distance D increases during the period from time T2 to T3. Time T2 is the time when vehicle 1 began to reverse, and time T3 is the time when a predetermined time length has elapsed from time T2. The predetermined time length is a preset value. The slip detection unit 17 monitors the time change of the remaining distance D and determines that vehicle 1 has slipped when the remaining distance D continuously increases over the predetermined time length.

[0035] In the example shown in Figure 3(b), the slip detection unit 17 detects that the remaining distance D is continuously increasing over a predetermined time period at time T3, and determines that the vehicle 1 has slipped. Once it is determined that the vehicle 1 has slipped, the slip detection unit 17 outputs information indicating the occurrence of slippage to the control unit 16.

[0036] When the vehicle 1 is detected to be sliding backward, the control unit 16 controls the braking device 6 to apply a second braking force to the vehicle 1 that is greater than the first braking force. The second braking force is large enough to stop the vehicle 1 from sliding backward. As shown in Figure 3(a), when the second braking force is applied to the vehicle 1 at time T3, the reverse speed of the vehicle 1 decreases, and the vehicle 1 stops at time T4. At this time, the position where the vehicle 1 stops is close to the target stopping position TP.

[0037] Furthermore, the control unit 16 may increase the second braking force as the road surface gradient angle θ acquired by the external sensor 3 increases. This ensures that the vehicle 1 does not slide backward. In order to stop the vehicle 1 from sliding backward earlier, the control unit 16 may shorten the time (time T3 to T4) it takes for the braking force of the vehicle 1 to reach the second braking force when the vehicle 1 is detected to slide backward.

[0038] The following describes the processing flow performed by the vehicle control device 10, with reference to Figure 4. Figure 4 is a flowchart showing the processing flow of the vehicle control device 10.

[0039] First, the vehicle information acquisition unit 11 of the vehicle control device 10 acquires vehicle information (step ST1). For example, the vehicle information acquisition unit 11 acquires the vehicle's location information and vehicle speed information as vehicle information. Next, the surrounding information acquisition unit 12 acquires surrounding information of the vehicle 1 (step ST2). For example, the surrounding information acquisition unit 12 acquires the location information of road signs and road markings around the vehicle 1, as well as the road surface gradient angle θ, as surrounding information.

[0040] Next, the target stop position setting unit 13 sets the target stop position TP (step ST3). For example, as shown in Figure 2, the target stop position setting unit 13 sets the position just before the stop line L located in the middle of the slope as the target stop position TP.

[0041] Next, the remaining distance acquisition unit 14 acquires the time change of the remaining distance D from the vehicle 1 to the target stopping position TP (step ST4). For example, the remaining distance acquisition unit 14 acquires the remaining distance D at a predetermined interval based on the position information of the stop line L included in the map information and the position information of the vehicle 1.

[0042] Next, the target deceleration determination unit 15 determines the target deceleration (step ST5). The target deceleration is the deceleration required to start decelerating the vehicle 1 at the deceleration start position P1 and stop the vehicle at the target stop position TP. Next, the control unit 16 determines whether or not the vehicle 1 has reached the deceleration start position P1 (step ST6). If it is determined that the vehicle 1 has reached the deceleration start position P1, the control unit 16 controls the braking device 6 to apply a first braking force to the vehicle 1 (step ST7). The first braking force is the braking force required to bring the deceleration of the vehicle 1 to the target deceleration. On the other hand, if it is determined that the vehicle 1 has not reached the deceleration start position P1, the determination in step ST6 is repeated until the vehicle 1 reaches the deceleration start position P1.

[0043] Next, the control unit 16 determines whether or not the vehicle 1 has reached the deceleration reduction position P2 (step ST8). If it is determined that the vehicle 1 has reached the deceleration reduction position P2, the control unit 16 reduces the first braking force (step ST9). This reduces the deceleration of the vehicle 1 and improves the ride comfort for the occupants. On the other hand, if it is determined that the vehicle 1 has not reached the deceleration reduction position P2, the first braking force is applied to the vehicle 1 until the vehicle 1 reaches the deceleration reduction position P2.

[0044] In step ST9, when the first braking force is released, the slip detection unit 17 determines whether or not the vehicle 1 is slipping (step ST10). For example, the slip detection unit 17 determines that the vehicle 1 is slipping when the remaining distance D continuously increases over a predetermined time period. If the vehicle 1 is slipping, the control unit 16 applies a second braking force to the vehicle 1 that is greater than the first braking force (step ST11). In other words, when the vehicle 1 is slipping, the braking force applied to the vehicle 1 is increased. This stops the vehicle 1 from slipping.

[0045] On the other hand, if it is determined that vehicle 1 is not sliding backward, the determination in step ST10 is repeated until sliding backward occurs. When vehicle 1 comes to a stop near the target stopping position TP, the braking control of vehicle 1 is terminated.

[0046] As explained above, when the vehicle control device 10 detects that the vehicle 1 is sliding backward, it applies a second braking force greater than the first braking force to the vehicle. This stops the vehicle 1 from sliding backward and allows the vehicle to stop near the target stopping position TP.

[0047] Although various embodiments of the vehicle control device 10 have been described above, various modified forms can be constructed without changing the gist of the invention, and the invention is not limited to the embodiments described above. The various embodiments described above can be combined to the extent that no contradictions arise. [Explanation of Symbols]

[0048] 1...Vehicle, 6...Braking system, 10...Vehicle control device, 14...Remaining distance acquisition unit, 15...Target deceleration determination unit, 16...Control unit, 17...Slip detection unit, D...Remaining distance, TP...Target stopping position, θ...Gradient angle.

Claims

[Claim 1] A vehicle control device, mounted on a vehicle equipped with a braking system, which performs braking control to stop the vehicle at a target stopping position, A remaining distance acquisition unit that acquires the time change of the remaining distance to the target stopping position, A gradient acquisition unit that acquires the gradient angle of the road surface on which the vehicle travels, A control unit that controls the braking device to apply a first braking force to the vehicle in order to stop the vehicle at the target stopping position, A sliding detection unit determines that the vehicle has started to slide when the remaining distance has continuously increased over a predetermined period of time, Equipped with, When the control unit detects that the vehicle is sliding backward, it controls the braking device to apply a second braking force to the vehicle that is greater than the first braking force and is sufficient to stop the vehicle from sliding backward. The control unit is a vehicle control device that increases the second braking force as the gradient angle increases.

Images